74,924 research outputs found
Coordination polymer chains built from CuII and adipate ions linked by hydrogen bonds to form a three-dimensional framework structure
No full textIn the title compound, catena-poly[bis[(2,2'-bipyridine-κ2N,N')(1,1,3,3-tetracyano-2-ethoxypropenido-κN)copper(II)]-μ4- hexanedioato-κ6O1,O1:O1 :O6,O6':O6], [Cu2(C9H5N4O)2(C6H8O4)(C10H8N2)2]n , the adipate (hexanedioate) dianion lies across a centre of inversion in the space group P. The CuII centre adopts a distorted form of axially elongated (4+2) coordination, and the CuII and adipate components form a one-dimensional coordination polymer from which the 2,2'-bipyridine and 1,1,3,3-tetracyano-2-ethoxypropenide components are pendent, and where each adipate dianion is bonded to four different CuII centres. The coordination polymer chains are linked into a three-dimensional framework structure by a combination of C-H⋯N and C-H⋯O hydrogen bonds, augmented by a π-π stacking interaction.Peer reviewe
Tris(2,2'-bipyridine)iron(II) bis(1,1,3,3-tetracyano-2-ethoxypropenide) dihydrate : chiral hydrogen-bonded frameworks interpenetrate in three dimensions
No full textThe authors acknowledge the Algerian Ministry of Higher Education and Scientific Research, the Algerian Directorate-General for Scientific Research and Technological Development, and Ferhat Abbas Setif 1 University for financial support.In the title compound, [Fe(C10H8N2)3](C9H5N4O)2·2H2O, the chiral cations lie across twofold rotation axes in the space group C2/c. The anions and the water molecules are linked by two independent O-H⋯N hydrogen bonds to form C22(8) chains, and these chains are linked by the cations via C-H⋯N and C-H⋯O hydrogen bonds to form two interpenetrating three-dimensional frameworks, each of which contains only one enantiomeric form of the chiral cation.Peer reviewe
Catena-Poly[[[4-amino-3,5-bis(pyridin-2-yl)-4H-1,2,4-triazole-κ2N1,N5](dicyanamido-κN)copper(II)]-μ2-dicyanamido-κ2N:N'] : coordination polymer chains linked into a bilayer by hydrogen bonds and π-π Stacking interactions
No full textThe authors acknowledge the Algerian DG–RSDT (Direction Generale de la Recherche Scientifique et du Developpement Technologique) and the Algerian ATRST (Agence Thematique de Recherche en Sciences et Technologie; PNR project) for financial support.In the title compound, [Cu(C2N3)2(C12H10N6)]n or [Cu(dca)2(abpt)]n, where abpt is 4-amino-3,5-bis(pyridin-2-yl)-H-1,2,4-triazole and dca is the dicyanamide anion, the CuII centre is five-coordinate with an approximately square-pyramidal geometry. One of the two dicyanamide ligands is a terminal ligand, but the other one acts as a μ1,5-bridging ligand between pairs of CuII centres, so generating a one-dimensional coordination polymer. A combination of N - H⋯N and C - H⋯N hydrogen bonds, augmented by π-π stacking interactions, links the coordination polymer chains into a bilayer structure. Comparisons are made with some related CuII complexes containing dca ligands and heteroaromatic co-ligands.Peer reviewe
An iron(II) complex of trans, trans, trans-bis(azido)bis(4-amino-3,5-bis(2-pyridyl)-1,2,4-triazole): insight into molecular and supramolecular structures using hirshfeld surface analysis and DFT studies
No full textThe solvothermal synthesis and structural characterization of the new high-spin iron(II) complex trans,trans,trans-[bis(azido)bis(4-amino-3,5-bis(2-pyridyl)-1,2,4-triazole)iron(II)] is reported. The complex crystallizes in the triclinic space group Pī with Z = 1, a = 6.6648(3) Å, b = 8.4012(3) Å, c = 11.7970(5) Å, α = 85.063(2)°, β = 95.063(2)°, γ = 98.5080(10)°. It is centrosymmetric with mutually trans pairs of azido, pyridyl and triazole N atoms, the Fe–N distances indicate a high-spin configuration. A combination of N–H···N hydrogen bonds and π···π stacking interactions generates a sheet structure in which the shortest Fe···Fe distance is 6.6648(3) Å. Hirshfeld surface analysis has been performed for visualizing, exploring and quantifying intermolecular interactions that stabilize the crystal packing of the complex. Non-covalent interactions present in the crystal structure have also been analysed by means of computational tools. The interaction energies associated with the different interaction topologies were calculated and QTAIM and NBO analyses were applied to study the origin and nature of the attractive forces.Fil: Setifi, Zouaoui. Université Ferhat Abbas; ArgeliaFil: Setifi, Fatima. Université Ferhat Abbas; ArgeliaFil: Glidewell, Christopher. University of St. Andrews; Reino UnidoFil: Gil, Diego Mauricio. Universidad Nacional de Tucumán. Instituto de Biotecnología Farmacéutica y Alimentaria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biotecnología Farmacéutica y Alimentaria; ArgentinaFil: Kletskov, Alexey V.. University of Russia; RusiaFil: Echeverria, Jorge. Universidad de Barcelona; EspañaFil: Mirzaei, Masoud. University of Mashhad; Irá
(Adipato-κ2O,O′)diaqua[bis(pyridin-2-yl-κN)amine]cobalt(II) trihydrate
No full textIn the monomeric title complex, [Co(C6H8O4)(C10H9N3)(H2O)2]·3H2O, the distorted octahedral CoN2O4 coordination environment comprises two N-atom donors from the bidentate dipyridyldiamine ligand, two O-atom donors from one of the carboxylate groups of the bidentate chelating adipate ligand and two water molecules. In addition, there are three solvent water molecules which are involved in both intra- and inter-unit O—H...O hydrogen-bonding interactions, which together with an amine–water N—H...O hydrogen bond produce a three-dimensional framework
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
Final word on Jersey Dutch
No full textIn this article, William Z. Shetter compares and contrasts the dialects that developed between different Dutch colonies in the New World. He explores in-depth the nuances of Jersey Dutch, and provides theories to explain how Dutch and colonial languages blended. The article is reprinted from American Speech, December 1958, Volum XXXIII, No. 4
The synthesis, characterization, X-ray structure and magnetism of dinuclear-based bis[μ-(1,1,3,3-tetracyano-2-ethoxypropenido-κ2N,N′) (1,1,3,3-tetracyano-2-ethoxypropenido-κN)(2,2′-bipyridine)copper(II)] organized in alternating chains via semi-coordinating Cu–N distances
No full textThe monoanionic ligand 1,1,3,3 tetracyano-2 ethoxypropenide (tcnoet) is reported with its Cu(II)–bpy complex of formula [Cu2(µ-tcnoet)2(tcnoet)2(bpy)2]. The structure has been determined using X-ray diffraction and features an alternating chain with bridging tcnoet ligands. One ligand acts as a bidentate, dinucleating ligand with one short Cu–N and one medium Cu–N bond, whereas the other tcnoet is largely monodentate, albeit with a very weak interdimer Cu–N bond. Despite the arrangement in dinuclear units, further arranged into linear chains through the non-bridging tcnoet ligand, the compound shows no significant magnetic exchange, as deduced from magnetic susceptibility down to 4 K. Ligand-field, IR and EPR spectra in the solid state and in frozen solution are reported and are consistent with the overall structure
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
Statistics of the subgrid scales after the shock-turbulence interaction
No full textThe interaction of a normal shock with isotropic turbulence (IT) represents a basic problem for studying some of the phenomena associated with high speed flows, such as hypersonic flight, supersonic combustion and Inertial Confinement Fusion (ICF). In general, in practical applications, the shock width is much smaller than the turbulence scales and the upstream turbulent Mach number is modest. In this case, recent high resolution shock-resolved Direct Numerical Simulations (DNS) (Ryu and Livescu, J. Fluid Mech., 756, R1, 2014) show that the interaction can be described by the Linear Interaction Approximation (LIA). By using LIA to alleviate the need to solve the shock, DNS post-shock data can be generated at much higher Reynolds numbers than previously possible. Here, such results with Taylor Reynolds number around are used to investigate the properties of the subgrid scales (SGS). In particular, it is shown that the shock interaction decreases the asymmetry of the SGS dissipation PDF as the shock Mach number increases, with a significant enhancement in size of the regions and magnitude of backscatter
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